Plug for a void, system and method

ABSTRACT

A plug for a void in a mine to divert water having a rigid closed cell foam which fills the void. The rigid closed cell foam having a plurality of pipes disposed within the foam. The pipes distributed throughout the void. The pipes are positioned in the foam so the pipes are staggered in length vertically with respect to various heights in the void, and the pipes are positioned in the foam every 4′ to 6′ horizontally with respect to the void. Each pipe has a mixing stick. A method for diverting water from a void in a mine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 17/107,265filed Nov. 30, 2020, now U.S. Pat. No. 11,421,532, which is acontinuation of U.S. patent application Ser. No. 16/654,697 filed Oct.16, 2019, now U.S. Pat. No. 10,851,652 issued Dec. 1, 2020, which is adivisional of U.S. patent application Ser. No. 15/993,018 filed May 30,2018, now U.S. Pat. No. 10,550,695 issued Feb. 4, 2020, all of which areincorporated by reference herein.

FIELD OF THE INVENTION

The present invention is related to a plug in a void of a longwall beingmined for coal. (As used herein, references to the “present invention”or “invention” relate to exemplary embodiments and not necessarily toevery embodiment encompassed by the appended claims.) More specifically,the present invention is related to a plug in a void of a longwall beingmined for coal where the plug is a rigid closed cell foam which fillsthe void having a plurality of pipes disposed within the foam.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofthe art that may be related to various aspects of the present invention.The following discussion is intended to provide information tofacilitate a better understanding of the present invention. Accordingly,it should be understood that statements in the following discussion areto be read in this light, and not as admissions of prior art.

Longwall mining is by far the most efficient means of extracting coal inunderground mines today. The longwall system consisting of the shearer,conveyor system, and hydraulic roof supports (shields) is constructed onone end of solid block of coal that ranges between 1000′ and 1,500′wide, and 2 to 4 miles long. Once constructed the longwall system minesthat entire block of coal taking cuts (passes) across the width of thepanel (the face). As the coal is being mined across the face, the roofabove must be temporarily supported to prevent the collapse of thematerial above. Once the shields advance to support newly exposed roof,they allow material that was once above them, to fall behind them.

The efficient advancement of these shield supports is where the presentinvention plays a key role. At times in Longwall mining, the immediateroof can deteriorate drastically between the time a cut is made, and theadvancement of the shield supports. In some cases, the roof conditionscan be so poor that the roof begins to fall immediately as the longwallmining machine cuts the face. When this occurs, a void is created abovethe shields that: 1) causes more material to fall onto the conveyor;usually in the form of large unmanageable pieces, and 2) preventsfurther advancement of the shields. The shield supports are connected tothe conveyor system. Their progression consists of 1) collapsing to thepoint where they are no longer in contact with the roof, 2) advancingforward to support newly exposed roof, 3) repressurizing against theroof, and 4) pushing the conveyor system forward to position it for thelongwall shearer's next pass along the face. If the shields extend fullybut are unable to pressurize against the mine roof due to a void, theconveyor system cannot move forward and thus the longwall mining processis stopped. While the process is stalled with exposed rock above,gravity continues to act on the exposed rock causing more material tofall. The more rock that falls, the larger the existing void becomes.The larger the void becomes, the more rock falls, and so on. The amountof time that gravity is allowed to act on a particular area ofunsupported top also serves to worsen the circumstances.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to a plug for a void in a mine. The plugcomprises a rigid closed cell foam which fills the void having aplurality of pipes disposed within the foam. The pipes distributedthroughout the void. The pipes are positioned in the foam so the pipesare staggered in length vertically with respect to various heights inthe void, and the pipes are positioned in the foam every 4′ to 6′horizontally with respect to the void. Each pipe has a mixing stick.

The present invention pertains to a method for forming a void in a mine.The method comprises the steps of adding a catalyst to a singlecomponent material. There is the step of providing the single componentmaterial with the catalyst to a pump which pumps only the singlecomponent material with the catalyst. There is the step of supplying airto the pump at a minimum of 90 psi while the pump is pumping the singlecomponent material with the catalyst through a first hose attached to afirst port of a y fitting. There is the step of supplying water at aminimum of 60 psi through a second hose to a second port of the yfitting so the water and single component material with the catalystmerge in the y fitting to create a product. The catalyst used being afunction of ambient temperature about the void and the watertemperature. There is the step of placing the product with a third hosethat extends from the y fitting on the outer most areas of the void andpumping back to the middle of the void, where the product expands whenthe product releases into the void from the third hose and cures to arigid closed cell foam to form a plug in the void.

The present invention pertains to a system for making a plug in a voidof a mine having a pressurized air source and a pressurized watersource. The system comprises a material source of a single componentmaterial. The system comprises a pump having an air pump inlet toreceive air from the air source and a material pump inlet to receive thematerial from the material source which pumps the material with the airat a minimum pressure of 90 psi out a pump outlet. The system comprisesa first hose attached to the pump outlet through which the air andmaterial is pumped from the pump. The system comprises a second hoseattached to the water source which receives water from the water sourceat least at a pressure of 60 psi. The system comprises a y fittinghaving a first port to which the first hose is attached which receivesthe air and material from the first hose, a second port to which thesecond hose is attached to receive water from the second hose, and athird port from which a product formed from the water from the secondhose and the material and air from the first hose flows out. The systemcomprises a third hose attached to the third port which receives theproduct from the y fitting, the third hose having a mixing stickdisposed in the third hose. The system comprises a plurality of pipes tobe disposed in the void which are configured to be connectedsequentially with the third hose through which product from the thirdhose flows into and through and out the pipes to foam and form the plug.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

In the accompanying drawings, the preferred embodiment of the inventionand preferred methods of practicing the invention are illustrated inwhich:

FIG. 1 is a schematic representation regarding the setup of the claimedinvention in a mine.

FIG. 2 is a schematic representation of the system of the claimedinvention.

FIG. 3 is a top view of a plug of the claimed invention in a void in amine.

FIG. 4 is a side view of a plug in a void in a mine.

FIG. 5 is a top view of shields advanced once the plug with a falsebottom is formed in the void in the mine.

FIG. 6 is a front view of plug with a false bottom in a void in a mine.

FIG. 7 is a top view of shields advanced once the plug without a falsebottom is formed in a void in a mine.

FIG. 8 is a front view of a plug without a false bottom which has filleda void in the mine.

FIG. 9 is a side view of a longwall shield, shearer and face conveyor.

FIG. 10 shows a recovery mesh on the longwall face in a roll andsuspended from the shield supports.

FIG. 11 shows hydraulic shields and shield supports, wall shearer andface conveyor.

FIG. 12 is a schematic representation of an operational mine.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals refer tosimilar or identical parts throughout the several views, and morespecifically to FIGS. 1, 3, 4, 7 and 8 thereof, there is shown a plug 10for a void 12 in a mine 14. The plug 10 comprises a rigid closed cellfoam 16 which fills the void 12 having a plurality of pipes 18 disposedwithin the foam 16. The pipes 18 distributed throughout the void 12. Thepipes 18 are positioned in the foam 16 so the pipes are staggered inlength vertically with respect to various heights in the void 12, andthe pipes 18 are positioned in the foam 16 every 4′ to 6′ horizontallywith respect to the void 12. Each pipe has a mixing stick 20.

The pipes 18 may be disposed in the plug 10 at least about every 10 feetapart lengthwise across the plug 10 and about at least every 5 feetapart depth wise across the plug 10. The plug 10 may include a falsefloor 28 from which the pipes 18 extend into the hardened foam 16, asshown in FIGS. 5 and 6 .

The present invention pertains to a system 66 for making a plug 10 in avoid 12 of a mine 14 having a pressurized air source 44 and apressurized water source 52, as shown in FIG. 2 . The system 66comprises a material source 72 of a single component material 40. Thesystem 66 comprises a pump 42 having an air pump inlet 68 to receive airfrom the air source 44 and a material pump inlet 70 to receive thematerial 40 from the material source 72 which pumps the material 40 withthe air at a minimum pressure of 90 psi out a pump outlet 74. The system66 comprises a first hose 46 attached to the pump outlet 74 throughwhich the air and material 40 is pumped from the pump 42. The system 66comprises a second hose 54 attached to the water source 52 whichreceives water from the water source 52 at least at a pressure of 60 psiwith a water valve 78 to stop or start the flow of water. The system 66comprises a y fitting 50 having a first port 48 to which the first hose46 is attached which receives the air and material 40 from the firsthose 46, a second port 56 to which the second hose 54 is attached toreceive water from the second hose 54, and a third port 62 from which aproduct 58 formed from the water from the second hose 54 and thematerial 40 and air from the first hose 46 flows out. The system 66comprises a third hose 60 attached to the third port 62 which receivesthe product 58 from the y fitting 50, the third hose 60 having a mixingstick 20 disposed in the third hose 60. The system 66 comprises aplurality of pipes 18 to be disposed in the void 12 which are configuredto be connected sequentially with the third hose 60 through whichproduct 58 from the third hose 60 flows into and through and out thepipes 18 to foam 16 and form the plug 10.

The present invention pertains to a method for forming a void 12 in amine 14. The method comprises the steps of adding a catalyst 38 to asingle component material 40. There is the step of providing the singlecomponent material 40 with the catalyst 38 to a pump 42 which pumps onlythe single component material 40 with the catalyst 38. There is the stepof supplying air to the pump 42 at a minimum of 90 psi while the pump 42is pumping the single component material 40 with the catalyst 38 througha first hose 46 attached to a first port 48 of a y fitting 50. There isthe step of supplying water at a minimum of 60 psi through a second hose54 to a second port 56 of the y fitting 50 so the water and singlecomponent material 40 with the catalyst 38 merge in the y fitting 50 tocreate a product 58. The catalyst 38 used being a function of ambienttemperature about the void 12 and the water temperature. There is thestep of placing the product 58 with a third hose 60 that extends fromthe y fitting 50 on the outer most areas of the void 12 and pumping backto the middle of the void 12, where the product 58 expands when theproduct 58 releases into the void 12 from the third hose 60 and cures toa rigid closed cell foam 16 to form a plug 10 in the void 12.

There may be the step of placing a plurality of pipes 18 throughout thevoid 12. The placing the product 58 step may include the steps ofconnecting the third hose 60 to a first pipe 22 of the plurality ofpipes 18 and flowing the product 58 to the first pipe 22 so the product58 flows out of the first pipe 22 into the void 12, after which theproduct 58 foams and hardens. The first pipe 22 having a mixing stick 20across which the product 58 flows in the first pipe 22. There may be thestep of connecting the third hose 60 to a second pipe 24 of theplurality of pipes 18 and flowing the product 58 through the second pipe24 so the product 58 flows out of the second pipe 24 into the void 12,after which the product 58 foams and hardens.

There may be the steps of disconnecting the third hose 60 on the firstpipe 22, closing a material valve 64 to stop flow of material 40 to theY fitting 50 and flushing the third hose 60 clean with water flowingfrom the water inlet of the Y fitting 50. The placing the pipes 18 stepmay include the step of placing pipes 18 in the void 12 at least aboutevery 10 feet apart lengthwise across the void 12 and about at leastevery 5 feet apart depth wise across the void 12. The placing theproduct step includes the steps of creating pockets in the plug beingformed when the product cures and hardens and then placing the productfrom the third hose into the pockets through pipes 18 disposed in thepockets to strengthen the plug against forces. The placing the pipes 18step may include the step of placing a false floor 28 at the void 12with a long wall shield. The pipes 18 extending from the false floor 28into the void 12.

In the operation of the invention, a plug 10 is created in a void 12 ina mine 14, as shown in FIG. 2 . The present invention utilizes StrataAFS foam 16 to form the plug 10. The Strata AFS is a high expansion foam16 material 40 that when properly applied as described herein, canexpand up to 30 times its size. The application of this product 58 intothe void 12 above the longwall 76 shields 34 both consolidates all theloose rock and creates a “false floor 28” that is able to withstand theset pressure of the longwall 76 shields 34 allowing them to advance.

The plug 10 is formed with a pump 42 positioned in one of the intakeentries travelways of the mine 14 and fluidically connected at an airinlet of the pump 42 to an incoming air supply line in the mine 14, asshown in FIG. 1 . The incoming air supply line is at a pressure ofbetween 90 and 120 psi and is commonly found in a mine 14. The material40, properly mixed with catalyst 38, is provided to the material 40 pumpinlet. A first end of a first half-inch diameter wire braided flexiblehose 46 is fluidically connected to a pump outlet 74 of the pump 42 andextends to a position in proximity to the void 12 in the mine 14 that isto be plugged. The length of the first wire braided flexible hose 46could be several hundred feet long.

A second end of the first wire braided flexible hose 46 is fluidicallyconnected through a material valve 64 to a first port 48 of a Y fitting50 to provide material 40 pumped by the pump 42 to the Y fitting 50. Awater line is fluidically connected with a second hose 54 through awater valve to a second port 56 of the Y fitting 50 to provide water tothe Y fitting 50. The water provided to the Y fitting 50 is at 60 psi orgreater and comes from a long wall shield in proximity to the void 12.In this way, the water line need only be about 30 to 50 feet long sinceit is coming from a long wall shield that is already positioned near thevoid 12. As an aside, as is customary, long wall shields 34 will belined up along the long wall face 82 of the mine 14.

Fluidically connected to a product 58 outlet/third port 62 of the Yfitting 50 is a first end of a third half-inch diameter wire braidedflexible hose 60. Inside the third half-inch diameter wire braidedflexible hose 60 are three mixing sticks 20 in series, with each mixingstick 20 having 12 flutes, so there is a total of at least 36 flutesinside the third wire braided flexible hose 60. A second end of thethird wire braided flexible hose 60 is fluidically connected to a pipevalve 80 of each pipe, in turn, to provide flowing product 58 to eachpipe.

In the void 12 to be plugged, pipes 18 are positioned to prepare thevoid 12 for the plug 10 formation. Pipes 18 are positioned verticallyabout every 10 to 12 feet in the void 12 along the length of the void 12and at the front of the void 12, as shown in FIGS. 3 and 4 . FIG. 3shows a top view of the void 12 with pipes 18 in the mine 14 and FIG. 4shows a side view of the void 12 with pipes 18 in the mine 14.Furthermore, additional pipes 18 are positioned vertically in the void12 and offset about 1 to 2 feet inward into the void 12 from the pipes18 positioned along the length of the void 12 and at the front of thevoid 12. More pipes 18 are further offset 1 to 2 feet inward into thevoid 12 from the additional pipes 18, as needed, until the depth of thevoid 12 is populated with vertically position pipes 18. In this way, thevoid 12 is populated with pipes 18 from the walls that define the void12 going forward to the front of the open face 82 of the void 12.

If the strata of the void 12 roof 26 has a rock or boulder structure orformation into which the top of the pipes 18 can be inserted to hold thepipes 18 in place, the pipes 18 which populate the void 12 are held inplace by being inserted between the rocks or boulders at the void 12roof 26, squeezed into the cracks between the rocks or boulders alongthe roof 26. If the void 12 roof 26 is generally clear, without any typeof rock or bolder structure in which the tops of the pipes 18 can beinserted so they can be held by the rock a bolder structure, a falsefloor 28 is used instead to hold the pipes 18 in position inside thevoid 12. The false floor 28 may be formed of plywood boards 30 that haveholes drilled in the boards 30, into which the pipes 18 are inserted, bywhich the pipes 18 are held in the board. The bottom of the pipes 18with their valves, extend below the board. The plywood boards 30 withthe pipes 18 sticking up, are positioned on the long wall shields 34 sothe plywood boards 30 extend out from the long wall shields 34 into thevoid 12 so the pipes 18 are positioned in the void 12 to populate thevoid 12. The pipes 18 are typically half-inch diameter PVC pipe schedule80.

Once the pipes 18 are in position in the void 12 and the y fitting 50 isconnected to the first and third wire braided flexible hoses and thesecond hose 54 of the water line, the material 40 is provided to thepump 42 along with the air and the pump 42 is activated so the material40 with air is pumped out of the pump 42 at a rate of about 18 to 40 Lper minute to the Y fitting 50, where the material 40 mixes with thewater from the water source 52; and additionally experiences furthermixing as the material 40 and the water pass through the flutes of thethree mixing sticks 20 in the third hose 60 to create the product 58.The mixing sticks 20 create a turbulent flow in the mixed water andmaterial 40 which enhances and facilitates the mixing of the material 40and the water to the desired level so that when the resultant product 58flows out of the top of the pipe, it immediately starts to foam 16.

The second end of the third wire braided flexible hose 60 is attached toa pipe valve 80 at the bottom of the pipe. The pipe valve 80 at thebottom of the pipe is open to allow the product 58 to flow through thepipe and out the top of the pipe. The pipe has a generally cylindricalwall which is solid so all of the product 58 pumped into the pipe onlyflows out of the top of the pipe and into the void 12.

When the product 58 leaves the top of the pipe, it immediately begins tofoam and spreads out as more product 58 flows out of the pipe. The face82 of the foam 16 that forms as the product 58 first comes out of thepipe continues to spread out from the pipe into the void 12 as it beginsto cure until it hardens within about a minute to two minutes. At somepoint within 1 to 2 minutes, the face 82 of the foam 16 will havehardened enough that it forms a wall causing the product 58 that comesout behind the foam 16 face 82 to start backing up and becoming moredense as the pressure builds from the product 58 that continues to comeout of the pipe, but now cannot continue to flow because the face 82 ofthe product 58, and the product 58 that has come out already hashardened. As the product 58 is continued to be pumped into the pipe, theproduct 58 will harden and eventually back up in the pipe until the pipeat or near the pipe valve 80 at the bottom of the tremie valve willfracture or burst because all of the product 58 that has flowed out ofthe third wire braided flexible hose 60 has hardened and effectivelyformed a wall preventing any further product 58 flowing through thepipe. At this point, the only place for the product 58 flowing out ofthe third wire braided flexible hose 60 into the pipe to go is tofracture or burst the bottom of the pipe. When the material 40 is mixed,the appropriate catalyst 38 is added to the material 40, based on theconditions in the void 12, so the product 58 will start foamingimmediately after the product 58 leaves the pipe.

The pipes 18 that are positioned at the outermost edge of the void 12along the void 12 wall, have product 58 pumped through them first, sothat the plug 10 is built up from the outer edges of the wall of thevoid 12 in, so the foam 16 that has hardened from a pipe can then beused to build and extend the plug 10 by having the foam 16 from a newpipe use the already hardened foam 16 from a previous pipe as a platformto further extend the plug 10. In regard to FIGS. 3 , for example, thethree pipes 18 that are closest to the right side of the void 12 haveproduct 58 flowed through them first, one at a time, as described above.Next, the three leftmost pipes 18 in the void 12 have product 58 flowedthrough them. Then, the next three leftmost pipes 18 in the void 12 haveproduct 58 flowed through them, and then the next three rightmost pipes18 in the void 12 have product 58 flowed through them. In regard to FIG.3 , which is a top view of the void 12, the proximity of the back of thevoid 12 in relation to the pipes 18 is also taken into account so thatthe foam 16 hardens and builds out from the back extremity of the void12 in towards the center and front of the void 12. In this way, the plug10 is slowly built up to fill the void 12. The pipes 18 remain insidethe hardened foam 16. Once the product 58 has foamed and hardenedthroughout the void 12, the plug 10 that is formed can withstand at aload of at least 4000 psi, whether it be from the mine 14 or waterflowing in the mine 14.

After the pumping of product 58 to a pipe is complete, by the base ofthe pipe fracturing or bursting, the material valve 64 of the Y fitting50 is closed so no further material 40 flows through the Y fitting 50.However, the water valve of the Y fitting 50 is kept open so that watercan continue to flow through the third wire braided flexible hose 60 andflush out and cleanse the third wire braided flexible hose 60. Once theflushing of the second wire braided flexible line is complete, typicallyafter a few minutes of only water flowing through it, the second end ofthe third wire braided flexible hose 60 is attached to the pipe valve 80of the next pipe through which product 58 is to be pumped, and thematerial valve 64 of the Y fitting 50 is then reopened so material 40 ata flow rate of between 18 to 40 L per minute mixes with the water andflows out of the next pipe. This process continues until each pipe hasbeen utilized to pump product 58 into the void 12.

The material 40 is a hydrophobic polyurethane, known as Strata AFS™.designed to be injected into rock fissures, gravel layers, joints,cracks and voids to fill voids and consolidate strata. It is ideal forcontrolling and diverting water, including high volumes of gushingwater. The material 40 is

-   -   Single Component    -   Cures to a rigid, closed cell polyurethane foam    -   Free foam expansion up to 30 times    -   Controlled reaction time    -   Catalysts required for optimal reactivity    -   Multiple catalyst options for accelerated reaction times    -   Resistant to most organic solvents, mild acids, alkali,        petroleum and micro-organisms    -   Contains no volatile solvents

The specific steps to form the plug 10 are as follows:

1. Pump 42 needs to be set up to run a single component material 40.Depending on the pump 42 being used, one piston might have to beunhooked to deliver product 58 to just one side of the pump 42; or if abigger gear driven pump 42 is used, material 40 is simply supplied toboth inlets of the pump 42. An example of a pump 42 that is used for theformation of a plug 10, as described herein, is called the MaximatorGX45 PH-B sold by Perforator in Germany.

2. Air needs to be supplied to the pump 42 at a minimum of 90 psi and awater separator needs to be added to the air line along with andautomatic oilier to lubricate the pump 42.

3. Pump 42 needs to be flushed with a pump wash or oil-based product 58to remove any moisture or water in or to the pump 42.

4. High pressure ½ ″ to ¾ ″ lines/hoses will be run from the pump 42 tothe job site and a high-pressure material valve 64 installed on the endof the line. A water line will be run from the closest source of waterwith a minimum 60 psi to the job site and a check valve and water shutoff valve installed. A Y fitting 50 will be installed and both thematerial 40 line and water line will be attached to the Y fitting 50,and a single supply hose will be added to the end of the Y fitting 50 toattach to the pipes 18 already installed in the roof 26 or project to bepumped.

5. Once the pump 42 is flushed and primed, all the lines running fromthe pump 42 to the work site need to be flushed as well to remove allmoisture to prevent the material 40 from prematurely being exposed towater and begin foaming.

6. Underground temperature and water temp. will determine which type ofcatalyst 38 we use. There are 3 types of catalyst; regular, fast, extrafast. Each catalyst has its own set reaction time depending on watertemp. Regular is typically about 120 seconds or 2 minutes, fast is 90seconds and extra fast is about 60 seconds. This is based on water tempsaround 60 degrees. Once the desired catalyst 38 is chosen, the catalyst38 needs to be mixed for 3 to 5 minutes before it is added to the resinside of the material 40. The reason to mix is to make sure that there isno settling or separation of the catalyst 38. The material 40 iscomposed of 55.7% Diphenylmethanediisocyanate, isomers and homologues asits active ingredient (specifically2,2-dimethyl-1-(methylethyl)-1,3-propanediyl bis(2-methylpropanoate) andis called Strata AFS; the fast catalyst is 2,2′-Dimorpholinyldiethylether 30-50% by volume and is called Strata AFS FAST; and the extra fastis 2,2′-Dimorpholinyldiethyl ether 50-100% by volume and is calledStrata AFS EXTRA FAST. All these catalysts and the Strata AFS can bepurchased from Strata Worldwide LLC, Canonsburg, PA 15317; and detailsand information regarding mixing of the Strata AFS and each of the threecatalysts can be obtained therefrom. A third catalyst, known as CUT CATPURE, 2,2′-Dimorpholinyldiethyl ether 10-20% by volume, is availablefrom GCP Applied Technologies, Cambridge, MA 02140.

7. Once the catalyst 38 is mixed, it is added to the resin side of thematerial 40. A paddle mixer is installed in the drum or tote dependingon the volume of work that needs to be done and turned on. While themixer is running, the catalyst 38 is slowly poured into the resin andallowed to mix for 15 mins or until a good roll of the material 40 inthe drum or tote is achieved. The mixer will continue to run until thematerial 40 is ¾ of the way down, at which point the mixer is moved tothe next drum or tote and the process is continued. The material 40,properly mixed with catalyst 38, is provided to the material pump inlet70. For purposes herein, material 40 downstream of the pump 42 isunderstood to be material 40 with catalyst 38.

8. A sample is pulled from the mixed material 40 and catalyst 38 and asmall amount is mixed with the water on site to obtain the set andreaction time of the product 58. This will allow the user to know thetime available to move from one pipe to the next pipe before the product58 will set up in the nozzle or line. If it is anticipated a shut downor the pump 42 goes down, the valves can be shut at the end of the linesand flushed with water to keep the lines clear.

9. Once the material 40 is mixed, it is gravity fed into the alreadyflushed and primed pump 42, using the material 40 to push the pump 42flush or oil-based product 58 out.

10. Once the material 40 has reached the end of the first hose 46, wateris added to the Y, just to verify the pump 42 flush or oil is completelycleaned from the lines. Once it is verified the lines are clear and thefoam 16 is reacting to the water like it should, the third hose 60 isready to be hooked to the pipes 18 and pumping is started.

11. If the void 12 to be plugged is largely fractured rock that a falsebottom could not be constructed in, mixing sticks 20 can be added to thepipe to achieve a quicker set up of the foam 16. 3 mixing sticks with 12flutes per stick can be added to give the product 36 revolutions ofmixing prior to leaving the pipe, which will eliminate the product 58from just running down until the reaction time of the catalyst 38 hasbeen reached.

12. Starting to apply the foaming product 58 at the point where the fallor cave or void 12 has returned back to the normal height of the seamswill allow the hardened foam 16 to reach the highest compressivestrength to eliminate the rock from spalling or falling out any further.

13. Based on the height of the void 12 and the length of the void 12,numerous pipes 18 will be installed are various heights and widths tomake sure all areas of the void 12 or cavity will be filled.

14. A typical void 12 or cavity will have pipes that extend up 20′, 15′,and 10′ in height to make sure that all levels are covered, and every 4′to 6′ on the horizontal and 1′ to 2′ in depth.

15. Pumping through pipes 18 will typically start on one end of the fallthen move to the other end of the fall, then jump every other to everythird pipe, then back to the pipes 18 in-between until feedback out ofthe pipes installed at the 10′ or 15′ marks is achieved. Several pipeswill be left towards the ends and middle in pockets that have beencreated in the plug being formed to come back to and pressure everythingup. The pockets are created by pumping the product so it hardens atspaced apart locations in the void 12 but which link together alongtheir extremity so defined closed pockets are created. In these confinedspaces that the pockets define, the product is pumped into. The closedpocket allows the product to build up in pressure, since the product hasnowhere else to flow. The pumped product continues to flow into thislimited confined space of the pocket and continues to become denser anddenser as it cures. The cured and hardened product in the pocket isconsequently denser than the initial product that was pumped to form thepockets, since there is no confined space yet defined to allow theproduct to collect and become denser as it cures and more product flowsinto the same space. Instead, the initial flow of product does to someextent pressurize on itself by the front or lead of the product thatflows out and foams and cures defining a front wall with the productthat flows out of the same pipe that follows runs up against this newlycreated front wall and starts backing up and building up off the frontwall until the product cures and hardens in the pipe and preventsfurther product from flowing. These front walls of hardened product arethen used to build upon with subsequent product flowing out of otherpipes strategically positioned in the void 12 to create the pockets andbuild off of the newly defined front faces of product that has alreadyflowed out of other pipes already. Basically, one is trying to achieve abox or frame around the void 12, then the inside of the box around thevoid 12 is pressured up to achieve the highest compressive strengthpossible. Pipes are positioned inside the box at various heights toprovide the product to the inside of the box and fill the box which is aconfined closed space.

16. Once pumping is complete, the pump 42 is shut off and the materialvalve 64 at the end of the first hose 46 of the material 40 line isclosed and the end of the Y fitting 50 is flushed out with water toclear out the product 58 from the Y fitting 50 and third hose 60. Thewater line is unhooked from the first hose 46, and pump flush or anoil-based product 58 is run through the first hose 46 to remove any ofthe product 58 left in the first hose 46. Once everything is run out ofthe hoses, a bypass valve is opened on the pump 42 and the pump 42 isflushed out to remove any material 40.

17. The piston and valve would then be cleaned on the pump 42 and pistonre-honed and the pump 42 would be lubricated and made ready for the nextjob.

The following is an example of the application of Strata AFS highexpansion foam 16 on 10 Right Longwall Panel at Tunnel Ridge Mine (WV)for the purpose of securing unstable roof conditions and allowing theprogression of longwall system 66 to advance.

Tunnel Ridge Project.

The Circumstances on the 10 Right longwall panel at Tunnel Ridge minewere unique in that their longwall 76 was only 31.5 feet from itscompletion and subsequent recovery. The recovery process requires that alarge piece of industrial strength polymer mesh be installed above theshield supports 36 prior to the completion of the panel. A large roll ofmesh, roughly 35′ wide×the length of longwall 76 face 82, is pulled ontothe longwall 76 face 82 roughly 35′ (10 passes) prior to the end of thepanel. The roll is then suspended from the tips of the shields 34 andmade to drape over top of the shield canopies as the shields 34 advanceon each of the final 10 passes. The mesh unrolls between the shields 34and the exposed roof 26. Here, the recovery mesh had already been pulledonto the longwall 76 face 82 but had not yet been draped over the shieldcanopies. The roof 26 had begun to deteriorate and several differentvoids were present along the face 82 totaling an area of roughly 460′long×6′ high×6′ wide. Voids of a much greater magnitude have beensuccessfully filled, including some that have measured over 50′ high,with massive pieces of loose sandstone exposed. The major concern forthis project however, was the limited distance left to advance in thepanel; and the inability to initiate the “draping” of the mesh over theshield canopies for recovery. A significant amount of loose material 40laying on the shields 34 and the absence of a competent roof 26 to“pinch” and hold the mesh above the canopies had halted productionentirely.

The process.

Either end of the longwall 76 face 82 is referred to as a Gate End. Theend where power and fluid are supplied; and the coal travels off thesection is known as the Headgate. The opposite end of the longwall 76system 66 is known as the Tailgate. The gate ends are series of tunnels(entries and crosscuts) that were developed prior to the installation ofthe longwall 76 system 66, around the rectangular block of coal thatmakes up the longwall 76 panel, by another method known as ContinuousMining. The gates provide access to the longwall 76 face 82 for miners,equipment, supplies, and fresh air. The materials needed to complete theproject were delivered to the mine 14 and sent underground to theTailgate of affected longwall 76.

These materials consisted of:

1. 80 kits of Strata AFS 2-part foam material—each kit consists of 1)55-gallon drum and 1) 5 gallon can of STRATA AFS FAST catalyst 38.

2. 1 pump to transfer material from the tailgate to the affected areasof the longwall 76 face 82.

3. 1,200′ of ½ ″ staple lock hose. The staple lock hose comes in 50′sections and is coupled together from the pump 42 to the affected area.

4. 60 sections of ½ ″ PVC pipe and accompanying fittings. PVC pipeserves as the pipe and is used at the injection sites to disperse thematerial into the void 12 once mixed with water. PVC pipes are oftenconnected together by the men operating the nozzles (nozzle men) toreach different distances.

5. 50 sheets of ½ ″ plywood and 50 2×4′s. Plywood and 2×4′s are used tocreate a temporary false floor 28 from the tips of the shield supports36 to the coal face 82 wherever the distance between them cannot besealed by other means. The 2×4′s act as poles 32 to support the ends ofthe plywood sheets hanging off the shield supports 36.

6. 20 “Foam Packs”. Foam packs are also a 2-part expansive foam materialused on a much smaller scale in the mining industry for sealingventilation controls in the mine 14. They are similar to foam insulationyou can buy in a hardware store. Foam packs are used to seal gaps at andaround the injection site. Small gaps are present between shieldsupports 36, between sheets of plywood etc. These are almost always acompany supplied item.

7. 1 Strata Job Box. The job contains various fittings, tools, spareparts and accessories for the project.

8. 500′ of 1″ air hose. 1″ air hose supplies compressed air to theStrata pump 42 from a larger pipe already present in the mine 14, orfrom an onsite compressor if “mine air” is not present or is of aninadequate volume.

Set Up

Set up for the foam project at Tunnel Ridge began as soon as therequired materials reached the Tailgate section. The set-up process tookapproximately 2 hours.

The set-up process consisted of:

Pump 42 Station Set up.

1. The pump 42 was set up in the Tailgate entry, just out by thelongwall 76 face 82. The pump 42 was connected to the mine's 4″ airlineusing the Strata supplied 1″ air hose. Several kits of foam 16 weredelivered to the pump 42 in preparation to dispense material. 1″ suctionand ½ ″ discharge hoses were connected to the pump 42.

2. ½ ″ staple lock hose was stretched out and coupled together from thepump 42 all the way to the Headgate end of the affected area to form thefirst hose 46.

3. Once the pump 42 and lines were established, 8) five-gallon cans ofhydraulic oil were cycled through the pump 42 and discharge line toflush any moisture from all components. Once the catalyst 38 is added tothe ASF material, the presence of moisture in the pumping system 66 ordischarge line will react with the material and render them inoperable.

Preparation of the affected areas on the longwall 76 face 82.

1. For this application, the ½ ″ plywood was cut into 4′×4′ sections andhand carried along with 2×4′ s to the affected areas to build the falsefloor 28 between the shield tips and the face 82 from which the void 12extended. Construction of false flooring began on the area closest tothe Tailgate first and progressed toward the Headgate. The plywood wasplaced over top of the shield tips and against the coal face 82. 2×4′swere cut to desired height at the affected areas and installed beneaththe plywood to brace it off of the mine 14 floor.

2. Company supplied foam 16 packs were also carried on the face 82 andused to seal small cracks present between shields 34, plywood etc. toprevent or greatly limit the discharged product 58 from possibly leakingthrough the false floor 28 before it cures and be wasted.

3. Various lengths of PVC pipe were installed as the plywood floor wasconstructed for later use to pressurize the foam 16 after initiallyfilling the void 12. Lager access holes were also left in the falsefloor 28 roughly every 30′ for the nozzle men to observe theapplication.

Injection of AFS.

1. 30 minutes prior to completion of the setup, 1) five-gallon can ofcatalyst 38 shaken well and poured into the first 55-gallon drum of AFSmaterial. The air powered mixer was inserted into the drum and beganmixing the two components together. Adequate mixing of both parts iscrucial to the desired end product 58. Each kit was mixed for a minimumof 30 minutes before being injected on the face 82. The mixer was movedto the next kit when the previous kit was ½ empty. The same generalrules apply when using totes vs. 55-gallon drums. A tote is equivalentto five kits of AFS. Therefore 5) five-gallon buckets of catalyst 38 areadded to each tote and it is mixed until ½ empty before moving the mixerto the next tote.

2. The material injection line of the first hose 46 is connected to thefirst input port on a staple lock “Y” fitting at the injection site. Theother input side, the second input port, of the Y contains the ½ ″staple lock water supply line of the second hose 54. The water supplyhose is connected to the water system 66 on the longwall 76 shieldsupports 36, which act as the water source 52. A check valve isinstalled in the water supply line of the second hose 54 to ensure thatAFS material cannot enter the shield water system 66. The output port,the third port 62, on the Y fitting 50 is connected to a length of PVCpipe with the third hose 60 having the mixing sticks 20 that ultimatelydelivers the final product 58 to the affected area. The staple lock Yfitting 50 is where AFS mixes with water to form the product 58 thattravels to and through the PVC pipe. There are shut off valves locatedon both the material 40 and water supply hoses at the Y to regulate theflow of both liquids.

3. Within 60 to 90 seconds of being dispensed from the PVC pipe, AFSbegins to expand rapidly filling the void 12. The nozzle men are able tomove the PVC pipe and direct the flow of material 40. Nozzle men observefor leaks beneath the shields 34 while applying the material 40,constantly adjusting the direction of flow and working the material 40closer to them until they must seal the access hole and continue fillingthe void 12.

4. Once the void 12 is filled, previously installed PVC pipes areconnected to the Y fitting 50 in turn and more material 40 is injectedto pressurize the foam 16. The pressurizing of the material 40 gives itthe strength to withstand the set pressure of the shield supports 36.

5. This process continued toward the headgate end of the affected areauntil all voids were filled.

Upon completion of the foam 16 application, the shields 34 can beadvanced freely with no effect on or from the preexisting bad roof26/void 12. In the case of Tunnel Ridge, AFS successfully filled thevoid 12 and captured all loose rock that was present above the shieldsupports 36. Draping the recovery mesh over top of the shield canopieswas no longer an issue and the product 58 allowed the shields 34 topressurize and advance from that point forward.

Example 2

Blue Mountain Energy Deserado Mine located in Rangely, Colorado washaving issues with their top falling above their shields 34 in thelongwall 76. The top was caving in above the longwall 76 shields 34 fromshield 98 to 114 anywhere from 20 to 100 feet high and 90 feet long.

After getting material 40 and equipment to the mine 14, the pumpingstation was set up in the last open cross cut of the longwall 76; whichconsisted of a Maximator pump, 275-gallon totes of Strata AFS, 5-gallonpails of Strata EXTRA FAST catalyst 38, and an air driven drum mixer.Job boxes were brought in with the tools and fitting needed to pump foam16; which included ½ inch Y′s, ½ inch valves, ½ inch PVC couplers, ½inch staples, ½ inch×10 ft. PVC pipe, ½ inch 5075 PSI hose assemblies @50 ft. lengths, 50 ft. of clear 1-inch suction hose, PVC cement andprimer, ½ inch F×F coupler, ½ inch check valves, and assortment of handtools used to perform the job. The mine 14 air was connected to the pump42 and mixer and the mixing process was started.

The mixing process of Strata AFS and 5-gallon pails of Strata EXTRA FASTcatalyst 38 proceeded, which are 5 five-gallon pails per tote. Thepurpose of the catalyst 38 determines the reaction time of the material40 to start foaming. There are 3 types of catalysts 38. They are CUT CATPURE, Strata FAST, and Strata EXTRA FAST. For this specific job, StrataFAST and Strata EXTRA FAST catalyst 38 was chosen as best for thisapplication because of the size and area of the open void 12. While thetote was mixing, a half inch staple lock high pressure hose was run tothe affected area going to be pumped. It was approximately 800 feet frompump 42 to caved area. After the half inch line was set up, theconstruction of the false roof 26 began.

A false floor 28 was built between the shield tips and the longwall 76face 82. It was anywhere from 8 foot to 12-foot tip to face 82. Thefalse roof 26 consists of ½ inch plywood, 2×4′s and also 2×12′s. The2×12′s were run from the tip of the shield out to the face 82 of coalwith a 2×4 on the face 82 side of the 2×12 as a kicker to support andhold up the 2×12 and plywood. After the forms were up and stable, theplywood was installed plywood.

After the false floor 28 was complete the half inch PVC pipe was run.Typically, 1-2 PVC pipes were installed at every shield in the affectedarea. One was installed at the tip of the shield and one was installedat the face 82 of the coal. The PVC pipes are usually 10-30 foot but thesize can vary and they are placed above the shield. Once all the PVCpipes are installed, a mine 14 foam pack is used to seal up any holes orcracks in the plywood false floor 28, which helps prevent the Strata AFSfrom leaking through the false flor. While the false floor 28 is beingbuilt, a communication line is run from the pump station to the cavearea.

Next, hydraulic oil is pumped through the pump 42 and ½-inch material 40line to get out any moisture in the material 40 line or pump 42. Afterhydraulic has been pumped through the line, the suction end of the pump42 is connected to the tote of Strata AFS with a 1-inch clear suctionhose from the bottom of the tote. Strata AFS material 40 is then pumpedup the line until all the hydraulic is cleared and it is pure Strata AFSmaterial 40 in the first hose 46. A cup test is performed to make surethat the product 58 is performing as expected. After the cup testpasses, a 3-way Y fitting 50 is connected to the end of the first hose46. The first port 48 of the Y fitting 50 receives the material 40, thesecond port 56 of the Y fitting 50 is connected to a ½ inch water hosethat is coming off of the shield with a ½ inch check valve installed toprevent the Strata AFS material 40 to run back through the shields 34,and the third port 62 of the Y fitting 50 is the end that hooks upthrough the third hose 60 to a ½ inch female staplelock to PVC adapteron the PVC pipe in the false floor 28. Water is injected into thematerial 40 through the Y fitting 50. As the material 40 with catalyst38 and the water travels through the third hose 60 with mixing sticks 20and PVC pipes together, it mixes and begins the reaction of the StrataAFS and begins to start foaming.

On this specific job pumping was started at shield #104, which was themiddle of the cave. Pumping was started in a PVC pipe that was directedtowards the face 82 and 10 feet high. After pumping one tote throughthis PVC pipe, pumping was then moved to the PVC pipe that was at theshield tip on 104 which ran 20 ft. up into the cave area. After pumpinga tote through that pipe, pumping was moved down two shields 34 toshield #102, and then the process was repeated at shield #104. From#104, pumping was moved to shield #98 and the process was repeated.

Essentially, boxes of foam 16 are being built above the shields 34 inthe voided area by pumping at specific shields 34 first to create afoundation. To then help to be able to pressurize the foam 16 againsteach other to build the strength, it is necessary to consolidate therock and hold the foam 16 up above the shields 34. This process wasrepeated for the entire area of the cave which was shields 98-114. Thisresulted in pumping a blanket of foam 16 above the shields 34 up to 30ft. high from the face 82 to the tips of the shields 34 which then holdsup the loose material 40 above the shields 34 and doesn't allow therocks or material 40 to fall down through the shields 34 to theconveyer. This allows the shields 34 to pressurize against the foam 16ultimately resulting in allowing the longwall 76 shields 34 and conveyerto advance without further interruption, and in this case it did justthat. They were able to advance their shields 34 without any furtherrock falling into the conveyer.

The properties of Strata AFS, and the catalysts Strata AFS Fast andStrata AFS Extra Fast are as follows:

PROPERTIES

Strata AFS Resin Solids 100% ASTM D2369 Viscosity 200 cPs at 77° F. ASTMD2196 Color Black-Brown Liquid Density 1.10 g/cm3 ASTM D4659 Flashpoint293° F. ASTM D93  Corrosiveness Non-Corrosive

Strata AFS Cured Density confined 1.00 g/cm3 ASTM D3574 Density free 2PCF ASTM D3574 Compressive 4351 psi confined Flexural 2320 psi confinedFree Foam   4 psi unconfined

Strata AFS Fast Viscosity 20 cPs at 77° F. ASTM D2196 A ColorTransparent Red Liquid Density 0.973 g/cm3 Flashpoint 257° F. ASTM D93

Strata AFS Extra Fast Viscosity 20 cPs at 77° F. ASTM D2196 A ColorTransparent Red Liquid Density 1.000 g/cm3 Flashpoint 257° F. ASTM D93

REACTION TIMES

10% Strata AFS Fast Temp Start End Foam Factor 27° F. 30″ 1′40″ 20 V 40°F. 28″ 1′25″ 26 V 50° F. 26″ 1′23″ 26 V 60° F. 23″ 1′20″ 28 V 68° F. 23″1′20″ 30 V 77° F. 20″ 1′20″ 32 V

10% Strata AFS Extra Fast Temp Start End Foam Factor 27° F. 25″ 1′15″ 24V 40° F. 23″ 1′10″ 28 V 50° F. 23″ 1′10″ 28 V 60° F. 23″ 1′05″ 30 V 68°F. 20″ 1′05″ 30 V 77° F. 18″ 1′05″ 32 V

FIG. 9 is a side view of a longwall 76 shield, shearer and face 82conveyor. Shields 34 drop, advance, repressurize, and push the conveyorforward as the shearer makes passes. (FIG. 9 shows an additionalconveyor behind the shields 34, not applicable to aforementioned examplewhere immediate roof is rock and not coal).

FIG. 10 shows a recovery mesh is initially pulled onto the longwall 76face 82 in a roll and suspended from the shield supports 36. The end isdraped over the shield supports 36 and it unrolls between the shields 34and the roof 26 as the shields 34 advance.

FIG. 11 shows hydraulic shields 34 with shield supports 36, wall shearerand face conveyor.

FIG. 12 is a schematic representation of an operational mine 14.

Although the invention has been described in detail in the foregoingembodiments for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be described by thefollowing claims.

The invention claimed is:
 1. A method for forming a plug in a minecomprising the steps of: placing a plurality of pipes throughout thevoid; adding a catalyst to a single component material; providing thesingle component material with the catalyst to a pump which pumps onlythe single component material with the catalyst; supplying air to thepump while the pump is pumping the single component material with thecatalyst through a first hose attached to a first port of a y fitting;supplying water through a second hose to a second port of the y fittingso the water and single component material with the catalyst merge inthe y fitting to create a product, the catalyst used being a function ofambient temperature about the void and a temperature of the water; andplacing the product with a third hose that extends from the y fitting onouter most areas of the void and moving the product to a middle of thevoid, where the product expands when the product releases into the voidfrom the third hose and cures to a rigid closed cell foam to form a plugin the void, wherein the placing the product step includes the steps ofconnecting the third hose to a first pipe of the plurality of pipes andflowing the product to the first pipe so the product flows out of thefirst pipe into the void, after which the product foams and hardens, thethird hose having a mixing stick across which the product flows into thefirst pipe.
 2. The method of claim 1 including the step of connectingthe third hose to a second pipe of the plurality of pipes and flowingthe product through the second pipe so the product flows out of thesecond pipe into the void, after which the product foams and hardens. 3.The method of claim 2 including the steps of disconnecting the thirdhose on the first pipe, closing a material valve to stop flow ofmaterial to the Y fitting and flushing the third hose clean with waterflowing from the water inlet of the Y fitting.
 4. The method of claim 3wherein the placing the pipes step includes the step of placing pipes inthe void at least about every 10 feet apart lengthwise across the voidand about at least every 5 feet apart depth wise across the void.
 5. Themethod of claim 4 wherein the placing the product step includes thesteps of creating pockets in the plug being formed when the productcures and hardens and then placing the product from the third hose intothe pockets through pipes disposed in the pockets to strengthen the plugagainst forces.
 6. The method of claim 5 wherein the placing the pipesstep includes the step of placing a false floor at the void with a longwall shield, the pipes extending from the false floor into the void. 7.A plug for a void in a mine comprising: a rigid closed cell foam whichfills the void having a plurality of pipes disposed within the foam, thepipes distributed throughout the void, the pipes are positioned in thefoam so the pipes are staggered in length vertically with respect tovarious heights in the void, and the pipes are positioned in the foamstaggered horizontally with respect to the void, the void is above alongwall shield and the plug for the void both consolidates all looserock in the void and creates a false floor that is able to withstand aset pressure.
 8. The plug of claim 7 wherein the pipes are disposed inthe plug at least about every 10 feet apart lengthwise across the plugand about at least every 5 feet apart depth wise across the plug.
 9. Theplug of claim 8 including a false floor from which the pipes extend intothe hardened foam.